CT AND MR-IMAGING OF SQUAMOUS-CELL CARCINOMA OF THE TONGUE AND FLOOR OF THE MOUTH

Because contemporary treatment of oral cavity cancer involves procedur es that spare the tongue and mandible, an adequate assessment of the o ral cavity is essential for appropriate surgical and radiation therapy planning, Computed tomography (CT) and magnetic resonance (MR) imagin g, which allow differentiation between soft tissues, are valuable tool s for assessing this complex region, Their main advantage resides in t heir capacity to show at best the normal anatomy and the exact extent of a low-lying tumor, For display of soft tissues and tumor, MR imagin g, being a multiplanar and multicontrast technique, is superior to CT, Nonenhanced TI-weighted MR imaging is better for defining the exact e xtent of medullary bone invasion, which appears as a low-signal-intens ity area within hyperintense medullary fat, CT is optimal in detection of cortical bone invasion, which appears as an interruption or erosio n of the peripheral hyperattenuating rim, Thus, in cancer of the tongu e, MR imaging should be performed first, If tumor extension to the man dible is suspected (due to clinical or MR imaging findings), CT should be added, In a cancer of the floor of the mouth, both MR imaging and CT should be performed in the initial work-up, especially in those cas es in which there is a clinical doubt about mandibular extension of di sease, The main drawback of both modalities is their lack of specifici ty; other methods are needed to discriminate between tumors and inflam matory or infectious diseases, particularly in the mandible, However, once the diagnosis has been confirmed histologically, treatment can be chosen based on complementary information obtained from CT and MR ima ging.